1. Field of the Invention
This invention relates to a system and method for improving printing and, more particularly, to a system and method for providing a plurality of whetting areas on a workpiece for the purpose of cooling and/or lubricating a doctor blade of a printing press when the workpiece is used therein.
2. Description of the Related Art
During a gravure printing process, a workpiece, such as a cylinder, is situated in the press with a portion thereof submerged in ink. As the cylinder rotates, areas on the cylinder receive ink and transmit the ink to a substrate, such as paper, plastic, film and the like in a manner conventionally known.
The press typically had a doctor blade which engaged a surface of the workpiece and wiped the excess ink off the surface, so that ink within the areas would be transmitted to the substrate.
Typically, the workpiece would be engraved with a plurality of areas which collectively correspond to one or more images. Unfortunately, when there were significant spans between adjacent areas along a circumferential direction, then the doctor blade began to heat to undesired levels, such as in excess of 200 degrees Fahrenheit. One problem with the doctor blade heating is that when it first encountered the ink associated with an image edge of the engraved image area which defined the image to be printed, the doctor blade would be so hot that it would cause the ink along such image edge to evaporate.
Another problem with the doctor blade heating beyond a desired level is that it would begin to scratch the surface of the cylinder as the blade undergoes a thermo-dynamic expansion.
In the past, microcracks in the surface of the cylinder facilitated lubricating and cooling the doctor blade. Oftentimes, however, the microcracks were not deep enough to hold an appreciable amount of ink or did not provide enough lubrication to lubricate and/or cool the doctor blade. A workpiece which has very little engraved or etched area, will need more lubrication and, consequently, require more and deeper microcracks. Likewise, a cylinder which has a large portion of its surface area engraved or etched, requires less and shallower microcracks because the engraved or etched portion facilitates lubricating and/or cooling the doctor blade as it preforms its function.
In the past, small non-printing cells known as xe2x80x9cscum dotsxe2x80x9d were placed on the surface in response to a visual inspection of the cylinder in an attempt to overcome this problem. This empirical approach oftentimes resulted in too few or too many dots being situated on the cylinder, resulting in a doctor blade which was either not lubricated enough or lubricated to much.
Unfortunately, the processes heretofore known could not be selectively turned up or down to suit a cylinders specific lubrication needs. Furthermore, a leading edge of an engraved or etched area oftentimes does not print correctly. Because the doctor blade removes or causes some of the ink at the leading edge to be removed or evaporated. Surface tension and adhesion of the ink within an engraved or etched area to the walls defining the engraved or etched area is also thought to be a cause of poor printing quality.
What is needed, therefore, is a system and method for evaluating data and strategically positioning an appropriate number of whetting areas to facilitate eliminating or reducing the aforementioned problems.
It is, therefore, a primary object of the invention to provide a system and method for lubricating and/or cooling a doctor blade in a manner not previously known. Another object of the invention is to provide a system and method for strategically placing a plurality of whetting areas upstream of an engraved or etched image area, so that the resultant printing along a leading edge of an image associated with the engraved or etched area is improved.
In one aspect, this invention comprises a method for engraving/etching a plurality of whetting areas on a workpiece to facilitate lubricating and/or cooling a doctor blade when the workpiece is situated on a printing press, the method comprising the step of providing a system for engraving/etching a plurality of whetting areas at predetermined positions on the workpiece, the predetermined positions being determined in response to an image to be engraved or etched, a plurality of whetting areas being capable of holding ink for lubricating and/or cooling of the doctor blade when the workpiece is used in a printing press.
In another aspect, this invention comprises a method for locating a plurality of whetting areas on a workpiece to facilitate cooling and/or lubricating a doctor blade during a printing process, providing a whetting pattern determinor for determining a whetting pattern defining a plurality of whetting areas which facilitate cooling and/or lubricating the doctor blade in response to an image to be engraved or etched and providing a system for engraving/etching the whetting pattern and an image pattern corresponding to the image.
In still another aspect, this invention comprises a system for locating a plurality of whetting areas for facilitating cooling and/or lubricating a doctor blade on an printing press, comprising a whetting pattern determinor for determining a whetting pattern in response to an image to be engraved or etched, the whetting pattern determinor generating the whetting pattern of a plurality of whetting areas which facilitate cooling and/or lubricating the doctor blade in response to the image.
In yet another aspect, this invention comprises an engraving/etching system comprising a system for engraving/etching a workpiece with a plurality of areas defining an image pattern, a whetting pattern determinor for analyzing job data and for generating whetting data corresponding to a whetting pattern of whetting areas in response thereto and a signal generator for receiving the job data and the whetting data and for generating a signal in response thereto so that whetting pattern is engraved or etched relative to the engraved or-etched image pattern such that the whetting pattern facilitates cooling and/or lubricating a doctor blade in a printing press when the workpiece is used therein.
Other objects and advantages of the invention will be apparent from the following description, the accompanying drawings, and the appended claims.